Measurement and correlation of the adsorption equilibria of refrigerant vapors on activated carbon

Abstract

Adsorption equilibrium data have been measured for four refrigerant vapors (R-113, R-11, R-318, and R-22) on BPL activated carbon at three temperatures over a wide range of partial pressures using an automated isotherm apparatus. Special emphasis is placed on the design and operation of the apparatus to ensure the quality of these data. Isotherm data for each refrigerant vapor are analyzed for correct Henry's law behavior and correlated using three- and four-parameter functions with specified temperature dependencies. The functions employed in this study include (1) the Langmuir equation, (2) the Dubinin-Astakhov equation, (3) the virial equation, and (4) the modified Antoine equation. The Dubinin-Astakhov equation provides the best (or very comparable) fits, based on the variance, for R-113, R-11, and R-318. However, the Dubinin-Astakhov equation does not correctly describe the behavior of the R-22 data, resulting from its incorrect approach to Henry's law. Overall result show that, for adsorption of these refrigerants on BPL activated carbon, those correlations with exponents on the adsorbed-phase concentration terms greater than 1 generate the smallest variances.